/*
 * srtp_priv.h
 *
 * private internal data structures and functions for libSRTP
 *
 * David A. McGrew
 * Cisco Systems, Inc.
 */
/*
 *
 * Copyright (c) 2001-2006 Cisco Systems, Inc.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *   Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 *
 *   Redistributions in binary form must reproduce the above
 *   copyright notice, this list of conditions and the following
 *   disclaimer in the documentation and/or other materials provided
 *   with the distribution.
 *
 *   Neither the name of the Cisco Systems, Inc. nor the names of its
 *   contributors may be used to endorse or promote products derived
 *   from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 * OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 */

#ifndef SRTP_PRIV_H
#define SRTP_PRIV_H

#include "srtp.h"
#include "rdbx.h"
#include "rdb.h"
#include "integers.h"

/*
 * an srtp_hdr_t represents the srtp header
 *
 * in this implementation, an srtp_hdr_t is assumed to be 32-bit aligned
 *
 * (note that this definition follows that of RFC 1889 Appendix A, but
 * is not identical)
 */

#ifndef WORDS_BIGENDIAN

/*
 * srtp_hdr_t represents an RTP or SRTP header.  The bit-fields in
 * this structure should be declared "unsigned int" instead of
 * "unsigned char", but doing so causes the MS compiler to not
 * fully pack the bit fields.
 */

typedef struct {
    unsigned char cc :4; /* CSRC count             */
    unsigned char x :1; /* header extension flag  */
    unsigned char p :1; /* padding flag           */
    unsigned char version :2; /* protocol version    */
    unsigned char pt :7; /* payload type           */
    unsigned char m :1; /* marker bit             */
    uint16_t seq; /* sequence number        */
    uint32_t ts; /* timestamp              */
    uint32_t ssrc; /* synchronization source */
} srtp_hdr_t;

#else /*  BIG_ENDIAN */

typedef struct {
    unsigned char version:2; /* protocol version    */
    unsigned char p:1; /* padding flag           */
    unsigned char x:1; /* header extension flag  */
    unsigned char cc:4; /* CSRC count             */
    unsigned char m:1; /* marker bit             */
    unsigned pt:7; /* payload type           */
    uint16_t seq; /* sequence number        */
    uint32_t ts; /* timestamp              */
    uint32_t ssrc; /* synchronization source */
}srtp_hdr_t;

#endif

typedef struct {
    uint16_t profile_specific; /* profile-specific info               */
    uint16_t length; /* number of 32-bit words in extension */
} srtp_hdr_xtnd_t;

/*
 * srtcp_hdr_t represents a secure rtcp header
 *
 * in this implementation, an srtcp header is assumed to be 32-bit
 * alinged
 */

#ifndef WORDS_BIGENDIAN

typedef struct {
    unsigned char rc :5; /* reception report count */
    unsigned char p :1; /* padding flag           */
    unsigned char version :2; /* protocol version       */
    unsigned char pt :8; /* payload type           */
    uint16_t len; /* length                 */
    uint32_t ssrc; /* synchronization source */
} srtcp_hdr_t;

typedef struct {
    unsigned int index :31; /* srtcp packet index in network order! */
    unsigned int e :1; /* encrypted? 1=yes */
    /* optional mikey/etc go here */
    /* and then the variable-length auth tag */
} srtcp_trailer_t;

#else /*  BIG_ENDIAN */

typedef struct {
    unsigned char version:2; /* protocol version       */
    unsigned char p:1; /* padding flag           */
    unsigned char rc:5; /* reception report count */
    unsigned char pt:8; /* payload type           */
    uint16_t len; /* length                 */
    uint32_t ssrc; /* synchronization source */
}srtcp_hdr_t;

typedef struct {
    unsigned int version:2; /* protocol version                     */
    unsigned int p:1; /* padding flag                         */
    unsigned int count:5; /* varies by packet type                */
    unsigned int pt:8; /* payload type                         */
    uint16_t length; /* len of uint32s of packet less header */
}rtcp_common_t;

typedef struct {
    unsigned int e:1; /* encrypted? 1=yes */
    unsigned int index:31; /* srtcp packet index */
    /* optional mikey/etc go here */
    /* and then the variable-length auth tag */
}srtcp_trailer_t;

#endif

/*
 * the following declarations are libSRTP internal functions
 */

/*
 * srtp_get_stream(ssrc) returns a pointer to the stream corresponding
 * to ssrc, or NULL if no stream exists for that ssrc
 */

srtp_stream_t srtp_get_stream(srtp_t srtp, uint32_t ssrc);

/*
 * srtp_stream_init_keys(s, k) (re)initializes the srtp_stream_t s by
 * deriving all of the needed keys using the KDF and the key k.
 */

err_status_t srtp_stream_init_keys(srtp_stream_t srtp, const void *key);

/*
 * libsrtp internal datatypes
 */

typedef enum direction_t {
    dir_unknown = 0, dir_srtp_sender = 1, dir_srtp_receiver = 2
} direction_t;

/*
 * an srtp_stream_t has its own SSRC, encryption key, authentication
 * key, sequence number, and replay database
 *
 * note that the keys might not actually be unique, in which case the
 * cipher_t and auth_t pointers will point to the same structures
 */

typedef struct srtp_stream_ctx_t {
    uint32_t ssrc;
    cipher_t *rtp_cipher;
    auth_t *rtp_auth;
    rdbx_t rtp_rdbx;
    sec_serv_t rtp_services;
    cipher_t *rtcp_cipher;
    auth_t *rtcp_auth;
    rdb_t rtcp_rdb;
    sec_serv_t rtcp_services;
    key_limit_ctx_t *limit;
    direction_t direction;
    struct srtp_stream_ctx_t *next; /* linked list of streams */
} srtp_stream_ctx_t;

/*
 * an srtp_ctx_t holds a stream list and a service description
 */

typedef struct srtp_ctx_t {
    srtp_stream_ctx_t *stream_list; /* linked list of streams            */
    srtp_stream_ctx_t *stream_template; /* act as template for other streams */
} srtp_ctx_t;

/*
 * srtp_handle_event(srtp, srtm, evnt) calls the event handling
 * function, if there is one.
 *
 * This macro is not included in the documentation as it is
 * an internal-only function.
 */

#define srtp_handle_event(srtp, strm, evnt)         \
   if(srtp_event_handler) {                         \
      srtp_event_data_t data;                       \
      data.session = srtp;                          \
      data.stream  = strm;                          \
      data.event   = evnt;                          \
      srtp_event_handler(&data);                    \
}

#endif /* SRTP_PRIV_H */
